Tormentas cálidas en Chile central René D. Garreaud Departamento de Geofísica Universidad de Chile 28 de Mayo 2014 – DMC, Santiago Agradecimientos: Fondecyt 1110169, José Rutllant, Robert Rondanelli

Temario Revisión de trabajos previos Datos (Diarios DMC; 15’ DGF; CFSR; TMI/SMI…) Variabilidad de la línea de nieves e impactos hidro. Tormentas cálidas y frías Caso de estudio (Julio 2006) Análisis compuesto Modelo conceptual y conclusiones

Sistema Frontal + Depresión Extratropical Background Sistema Frontal + Depresión Extratropical Martes 20 de Mayo de 2014 ¿Que elemento(s) de gran escala son un buen predictor de la cantidad de precipitación?

Background Falvey & Garreaud 2007: Composite fields and Radiosonde profiles (local conditions) of CCh precipitation events.

Background Viale and Nuñez 2011: NNR Composite fields of CCh precipitation events. Extreme events exhibit sharper / more intense features than intense events.

More amplified/slower systems cause more precipitation Background Barret et al. 2012: Composite fields (QS sfc. Wind, TRMM, Z500, etc.) of CCh precipitation events. More amplified/slower systems cause more precipitation

Background Falvey & Garreaud 2007 Statistically robust correlation between CCh rainfall and low-level zonal moisture transport

Background Garreaud et al. 2013. Using PRECIS-ERA40 data, they show that strong (local) correlation between 850 hPa zonal wind and precipitation extends along south-central Chile because of the orographic enhancement in the windward side of the Andes a. r(U850,P) (a) (P,U850) Anual -0.8 -0.4 0 +0.4 +0.8

Eventos de precipitación también difieren en su temperatura 20 15 10 5 2900 2090 1320 Temperatura [°C] Altura Iso. 0°C [m] Tormenta fría Precipitación [mm/15 min] 20 15 10 5 2900 2090 1320 Temperatura [°C] Altura Iso. 0°C [m] Tormenta Cálida Precipitación [mm/15 min] 1 día ¿Es diferente el ambiente sinóptico entre TF y TC? ¿Cuan hábiles son los MPN en predecir Temp-Tormenta?

Hydrological Impacts Maipo en el Manzano river basin V=1 V=2 Potential Volume: P(h)dA Mean FL 3 May 1993 Mean FL 11 Jul 2006 Area below V=1 snow PDF Freezing level at SDO during rainfall events in Stgo V=2 snow Mean FL FL Height [m ASL]

Freezing level variability during winter storms (MJJAS) Ground based: Hsfc + Tm/sat Interpolated from Radisonde

Warm and cold winter rainstorms Warm storms (30%) Cold storms (65%)

Warm and cold winter rainstorms 6 4 2 -2 Composite local conditions (DGF, 30 min, 2004-11) during cold (44) and warm (22) rainstorms Surface pressure [hPa] [T]P12.5°C  H0  2900 m Air Temperature [°C] [T]P7.0°C  H0  1700 m 2 1 Precipitation Time [hr wrt storm onset]

Tormentas en Nahuelbuta +3 +2 +1 -1 -2 +2 +1 -1 -2 °C  T(4000 m) °C T(1200 m) +2 +1 -1 -2 Frontal passage °C  SAT 4 3 2 1 Rainfall Obs. Time [hr]

Uniform Precipitation Group exhibits colder conditions (H0 = 1900 m) Mountain Enhanced Precipitation Group exhibits warmer conditions (H0 = 2900 m)

Case of study: July 2006 DGF station Sto. Domingo radiosonde

Case of study: July 2006 Upper basin stations Lower basin stations

Case of study: July 2006 Wind profiles at Santo Domingo 12Z 11Jul 2006 Climo. data from FG2007

GOES12 IR2 + CFSR 500 hPa winds Case of study: July 2006 14Z 11jul2006

Case of study: July 2006 GOES-12 VIS (1445 UTC) + TRMM_3B42 daily precip. 11 July 2006

Case of study: July 2006 950 hPa winds, temperature and precipitation 18Z 11 Jul 2006

Case of study: July 2006 Lon-height cross sections at 33°W, 18Z 11 Jul 2006

Case of study: July 2006 Lat-height cross sections at 77°W, 18Z 11 Jul 2006

200 hPa winds, IPW and SLP. 12Z 11 Jul 2006 Case of study: July 2006 200 hPa winds, IPW and SLP. 12Z 11 Jul 2006

Case of study: July 2006 12z03jul 12z05jul 12z07jul 12z09jul 12z11jul

Case of study: July 2006 AM pass 11 Jul 2011 (b) SMI vapor and QS winds AM pass 11 Jul 2011 (a) TMI vapor and QS winds

Case of study: July 2006 TRMM_3B42 July 2006 07jul 08jul 09jul 10jul

Hovmoller section at 55°S of SLP Case of study: July 2006

Large scale composite analysis: IPW & 200 hPa wind CFSR averages for cold (44) and warm (22) rainstorms

Large scale composite analysis: SLP’ & T500’ CFSR averages for cold (44) and warm (22) rainstorms

Conceptual Model Rainfall at and behind cold front H0 < 2500 m ASL Prefrontal rainfall up in the Andes Well defined baroclinic wave Deep cyclone off southern Chile NW flow aloft Strong topographic blocking Northerly low-level jet Rainfall well ahead cold front H0 > 2500 m ASL Strong W flow aloft Conditionally unstable environment Reduced topographic blocking Wide, deep layer of ascent Weak trough farther south Blocking anticyclone farther west TransPacific zonal jet and troposheric river